Experimental and numerical investigations on seismic responses of reinforced concrete structures considering strain rate effect

The strain rate effect can inevitably impact the seismic responses of reinforced concrete (RC) structures because the dynamic properties of RC materials under earthquakes change significantly with the time-varying loading rates. This paper carries out systematic experimental tests and numerical simulations to investigate the effects of strain rates on the seismic responses of RC structures. The dynamic properties of micro-concrete and iron wire used in the shaking table specimen are firstly tested under seismic loading rates and the corresponding dynamic increase factors (DIFs) are estimated based on the test data. The shaking table test of a 1/5 scaled RC structure is performed to realistically reproduce the dynamic responses of RC structures with strain rate effect. Moreover, a three-dimensional rate-dependent fiber beam-column element is developed in the ABAQUS platform to establish the finite element (FE) model of the shaking table specimen, in which the estimated DIFs for the key parameters of micro-concrete and iron wire are employed to consider the strain rate effect. Besides, the rate-independent structural FE model is also developed using the traditional beam-column element with the static RC material constitutive models. The numerical results demonstrate that the seismic responses of RC structures are overestimated when the strain rate effect is neglected. As validated by the experimental data of the shaking table test, the FE model developed using the proposed rate-dependent fiber beam-column element can yield better structural seismic response predictions in comparison with the rate-independent model.